A vehicle traveling 60 miles per hour (MPH) moves 88 feet per second. In just one-tenth of a second at this speed, a vehicle travels 8.8 feet, which may be the difference between life and death in an accident event.
Typically in a vehicle, there is no connection between the steering wheel or its column and the braking system, unless the vehicle has special equipment installed to accommodate a handicapped driver. Historically, there has been a physical linkage between a brake pedal and a car's master cylinder. The brake pedal works as a force multiplying lever and uses this leverage to transfer the effort from the driver's foot to the master cylinder. The more quickly the master cylinder receives a “brake” signal, the faster a vehicle can be brought to a stop. However, the vehicle operator must 1) move his/her foot from the accelerator to the brake pedal, and then 2) depress the brake pedal a variable distance to physically engage the master cylinder to slow or stop the vehicle. Each of these motion activities requires a variable quantity of time.
With manual braking, the brake pedal uses leverage to transfer the effort from the driver's foot to the master cylinder. Different lever designs can alter the effort the driver needs to make, by using different levels of mechanical advantage. Brake pedals should be mounted securely, free from any excessive sideways movement, and at a height and angle that will allow the driver to quickly move from pressing the accelerator, or gas pedal, to applying the brakes.
The pedal is usually suspended from a bracket between the dash panel and the firewall, and works as a force-multiplying lever. If the power assist fails, the pedal's leverage is designed to allow the driver to still generate thousands of pounds of pressure at each wheel cylinder. Brake pedals must be free to return to their starting positions when pressure is removed. This allows the master cylinder pushrod to return to its un-depressed position.
Changes to how far the pedal can travel or to its resistance—if it feels harder or softer than normal—can be an indicator of problems such as low fluid levels or even a leak in the hydraulic system. When ABS brakes are activated during heavy braking, the pulsations of the system can be felt by the driver through the pedal and this is normal, however, a pulsating feel during normal or light braking can also be an indicator of a potential braking system problem.
Different brake lever designs and “power assist” developments have reduced the physical effort required by the driver on many vehicles. Certain newer vehicles may have an electronic linkage between the brake pedal and the master cylinder, which is sometimes described as a “brake-by-wire” system. An electronic braking system (EBS) utilizes electronics for the control side of the vehicle's braking system. An electronic signal replaces the air signal sent by the brake pedal to activate the brakes, improving stopping distances and braking system performance. The (EBS) introduced by Meritor WABCO is a brake-by-wire system that integrates anti-lock braking system (ABS) technology, automatic traction control (ATC) and other key vehicle control system features.
Vehicle braking systems have been disclosed which involve interactions with the steering wheel. EP 1263633 B1, for example, describes an apparatus comprising a brake actuating member mounted to the vehicle within hand reach of a driver. Strain gages are in communication with the brake actuating member, and a processing unit is connected to the strain gages for receiving input therefrom and for proportionally power-assisting the brake system of the vehicle. The driver, by exerting varying pressure by hand on the brake actuating member, controls the braking of the vehicle. In all embodiments, however, the vehicle operator physically moves a portion of the steering wheel or a paddle control mounted on the steering wheel. Such mechanisms are no more intuitive than moving one's foot onto a brake pedal, such that precious time may be wasted in an emergency.
Systems have also been described wherein parts of a steering wheel are “squeezed” to effectuate certain vehicular controls. Published U.S. Application No. 2012/0232751, for example, teaches operational controls including turn signal activation and deactivation, headlight brightening or dimming, windshield wiper activation and speed, and cruise control functions. In each case, portions of the steering wheel are “squeezed,” but there is no suggestion whatsoever regarding vehicle braking. Indeed, although the examples refer to sensing locations placed on the steering wheel, such locations could be placed at other locations in or on the vehicle where pressure may be applied by an operator (e.g., on a parking brake lever, a shift lever, a door handle, etc.). The reference clearly only anticipates control associated with vehicle movement as opposed to vehicle braking.